Can anyone tell which stores in London sell SIMM cards for Europe in general. I was hoping for a store location as staff would be available to help me get it set up on my phone. We land in Gatwick airport and I understand they have machines where you can buy SIMM cards, but I am not really tech savvy so I was hoping to get help with the task from staff who know what needs to be done. I do know that my phone is unlocked. I also know that some of the SIMM cards come with instructions - but in another language such as French, and as I don't know the language I am nervous about just picking up any old SIMM card. Thanks for any help you can provide me.
I always had good luck with Vodaphone; EE (a mélange of Orange and T-Mobile) and O2 are the other main carriers. Each has numerous stores. I used to like a store as well, have everything up and running when I walk out the door.
They are not legally obligated to include the EU in roaming plans anymore, so you need to discuss the details. If you will be in Switzerland, another non-EU country, then ask about that, as well as any other non-EU countries you might be in. Most likely still offer a plan with European roaming.
Of course, verify with your carrier that your phone is unlocked.
Be aware that since the UK is not longer in the EU, roaming charges may apply.
When I was in London in May I went to an EE store. The woman assisting me opened up my SIM slot and installed the new card. Service was working when I left 20 minutes later. She took my home SIM card put it back in a little plastic bag and sealed it with some tape. EE appears to offer free EU roaming on their pay as you go rates. Please do confirm with them if you should go with them.
https://shop.ee.co.uk/sim-only/pay-as-you-go-phones
At the top of that page in the link is a store finder. Pop in the post code of your lodging (or somewhere convenient) and it will show nearby shops